JP6927216B2 - Fluorine-containing polymer composition, fluororesin paint, painted articles - Google Patents

Description

The present invention relates to a fluorine-containing polymer composition, a fluororesin coating material, and a coated article.

A composition containing a fluorine-containing polymer and a solvent is suitably used as a raw material for a fluororesin coating material. The fluorine-containing polymer contained in the fluorine-containing polymer composition usually contains a fluoroolefin unit and a unit based on other monomers.
Patent Document 1 discloses a fluorine-containing polymer composition containing a fluoroolefin unit, a cyclohexyl vinyl ether unit, and a solvent.

Japanese Unexamined Patent Publication No. 61-174210

In recent years, as the applications of fluororesin coating materials have expanded, it has been required to further improve the storage stability of the fluoropolymer composition used as a raw material thereof. Here, the storage stability means that the mass average molecular weight of the fluorine-containing polymer contained in the fluorine-containing polymer composition does not increase under a heating environment.
The present inventor has produced a fluorinated polymer composition containing a fluorinated polymer containing a fluoroolefin unit and a cyclohexyl vinyl ether unit and a solvent with reference to the method described in Patent Document 1, and is stable in storage thereof. As a result of examining the sex, it was found that it may not meet the recent demand level.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a fluorinated polymer composition having excellent storage stability and a method for producing a fluorinated polymer.
Another object of the present invention is to provide a fluororesin coating material containing a fluorine-containing polymer composition and a coated article.

As a result of diligent studies to solve the above problems, the present inventors have found that the storage stability is affected by the presence of a predetermined impurity component in the fluorine-containing polymer composition, and further, the present inventions have found that the storage stability is affected by the presence of the predetermined impurity component. The present invention was completed by finding that a desired effect can be obtained by adjusting the amount within a predetermined range.
That is, the present invention is as follows.

[1] A composition containing a fluorine-containing polymer containing a fluoroolefin unit and a cyclohexyl vinyl ether unit and a solvent (excluding toluene and acetone), and the area ratio AR obtained by the following area ratio calculation method. A fluoropolymer composition containing 0.1 to 3%.
Area ratio calculation method: Add 200 parts by mass of acetone to 100 parts by mass of the fluorine-containing polymer composition to prepare a diluted solution obtained by diluting the fluorine-containing polymer composition, and further add to the total mass of the diluted solution. On the other hand, 1% by mass of toluene was added to the diluted solution to prepare a sample solution, and gas chromatography measurement was carried out using the obtained sample solution to obtain 0.5 times the peak area of the peak derived from toluene. A peak having the following peak areas is extracted, and the sum of the peak areas of the extracted peaks is defined as area A, which is derived from a component of the extracted peaks that appears on the side shorter than the retention time of cyclohexanol. Let the sum of the peak areas of the peaks be the area B, and let the value obtained by the following equation (1) be the area ratio AR.
Equation (1): Area ratio AR (%) = (Area B / Area A) × 100

[2] The content of the fluoroolefin unit is 30 to 70 mol% with respect to all the units contained in the fluorine-containing polymer, and the content of the cyclohexyl vinyl ether unit is the content of the fluorine-containing polymer. The fluorine-containing polymer composition according to [1], which is 10 to 50 mol% with respect to all the units contained.
[3] The fluorine-containing polymer composition according to [1] or [2], wherein the area ratio AR is 0.1 to 1.5%.
[4] The fluorine-containing polymer composition according to any one of [1] to [3], wherein the fluoroolefin unit is a tetrafluoroethylene unit or a chlorotrifluoroethylene unit.
[5] The fluorine-containing polymer composition according to any one of [1] to [4], wherein the fluorine-containing polymer further contains a unit having a crosslinkable group.
[6] The fluorine-containing polymer composition according to [5], wherein the unit having a crosslinkable group is a unit having a hydroxyl group.
[7] Any of [1] to [6], wherein the fluorine-containing polymer further contains a unit based on a fourth monomer other than a fluoroolefin, a cyclohexyl vinyl ether and a monomer having a crosslinkable group. Fluorine-containing polymer composition.
[8] The fluorine-containing polymer composition according to [7], wherein the unit based on the fourth monomer is a unit based on a monomer having no fluorine atom.

[9] A method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and a cyclohexyl vinyl ether, wherein the cyclohexyl vinyl ether is purified and contained in the cyclohexyl vinyl ether. , A fluorine-containing polymer characterized in that a cyclohexyl vinyl ether having the following area ratio of a compound having a boiling point lower than that of cyclohexanol is 0.15% or less, and the purified cyclohexyl vinyl ether is used for the polymerization. Manufacturing method.
Area ratio: In the measurement of cyclohexyl vinyl ether by gas chromatography, the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol with respect to the sum of the peak areas of all the peaks in the obtained gas chromatogram. Percentage of total area.
[10] The method for producing a fluorine-containing polymer according to [9], wherein the monomer mixture is polymerized in the presence of a solvent or a dispersion medium.

[11] A method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and a cyclohexyl vinyl ether in the presence of a radical polymerization initiator, an alkali metal carbonate and a polymerization solvent. The solvent is a mixed solvent of an alcohol having 1 to 6 carbon atoms and an organic solvent having a boiling point higher than that of the alcohol by 20 ° C. or higher. While removing the alcohol, the alcohol was distilled off under reduced pressure under the conditions that the temperature and degree of reduced pressure normally used for the vacuum distillation of the alcohol were exceeded and the organic solvent was not distilled off under reduced pressure, and the fluorine-containing weight dissolved in the organic solvent was obtained. A method for producing a fluorine-containing polymer, which comprises obtaining a coalescence.
[12] The organic solvent is an organic solvent having a boiling point of 110 ° C. or higher, the alcohol is ethanol, and ethanol is distilled off under reduced pressure at a temperature of 65 ° C. or higher and a reduced pressure of 45 Torr or lower. A method for producing a fluorine-containing polymer.
[13] The cyclohexyl vinyl ether according to [11] or [12], wherein the cyclohexyl vinyl ether contains a compound having a boiling point lower than that of cyclohexanol, and the following area ratio of the compound is 0.15% or less. A method for producing a fluorine-containing polymer.
Area ratio: In the measurement of cyclohexyl vinyl ether by gas chromatography, the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol with respect to the sum of the peak areas of all the peaks in the obtained gas chromatogram. Percentage of total area.

[14] A fluororesin coating material containing the fluorine-containing polymer composition according to any one of the above [1] to [8].
A painted article comprising the article [15] and a coating film formed on the article from the fluororesin coating material of [14].

According to the present invention, it is possible to provide a fluorine-containing polymer composition having excellent storage stability.
Further, according to the present invention, a fluororesin coating material and a coated article containing a fluorine-containing polymer composition can also be provided.

The meanings of the terms in the present invention are as follows.
The "unit" is a general term for an atomic group derived from one molecule of the monomer directly formed by polymerization of the monomer and an atomic group obtained by chemically converting a part of the atomic group. .. The content (mol%) of each unit with respect to all the units contained in the polymer is determined by analyzing the polymer by nuclear magnetic resonance spectral method. A unit based on a specific monomer is represented by adding a "unit" to the monomer name.
The "number average molecular weight" and the "mass average molecular weight" are values measured by gel permeation chromatography using polystyrene as a standard substance. The "number average molecular weight" is also referred to as "Mn", and the "mass average molecular weight" is also referred to as "Mw".
The "intermediate particle size" means a particle size that is 50% by mass by accumulating mass% from the smallest particle size.

As a feature of the fluorine-containing polymer composition of the present invention (hereinafter, also referred to as “the present composition”), the range of the area ratio AR obtained by the area ratio calculation method described in detail later is a predetermined range. There are points.
As a result of studying the prior art, the present inventors have found that a predetermined component (impurity component) contained in a trace amount in the present composition adversely affects the storage stability of the composition. Specifically, first of all, the present composition inevitably contains an impurity component derived from a monomer used for producing a fluorine-containing polymer. Examples of the impurity component include a residue of cyclohexanol used when synthesizing cyclohexyl vinyl ether, a by-product residue generated when synthesizing cyclohexyl vinyl ether, and the like. Among them, in gas chromatography measurement (hereinafter, also referred to as "GC measurement"), components appearing on the side shorter than the retention time of cyclohexanol (however, acetone, toluene and the like are included, as will be described later). However, the present inventors have found that it affects the storage stability of the composition.
Therefore, the present inventors have found that the storage stability is improved by controlling the content of the component to a predetermined amount or less. Although the detailed reason why the component is related to the storage stability is unknown, it is presumed that the storage stability is deteriorated because the component promotes cross-linking between the fluorine-containing polymers in the present composition. NS.

In the following, first, the calculation method of the area ratio AR (hereinafter, also referred to as “area ratio calculation method”) will be described in detail.
In this area ratio calculation method, GC measurement is used. The method for preparing the sample solution to be used for GC measurement is as follows.
First, a fluorinated polymer composition is prepared, and 200 parts by mass of acetone is added to 100 parts by mass of the fluorinated polymer composition to prepare a diluted solution obtained by diluting the fluorinated polymer composition.
Then, 1% by mass of toluene with respect to the total mass of the diluted solution is added to the diluted solution to prepare a sample solution. As will be described later, in the GC measurement, toluene is added as a reference for extracting the peak of the trace component contained in the fluorine-containing polymer composition.

Then, GC measurement is performed using the obtained sample solution.
The GC measurement is performed under the following conditions using a gas chromatograph (detector: FID) manufactured by Agilent Technologies.
(Sample injection volume) 1.0 μL (Injection mode) Split (Carrier gas) He (Injection port temperature) 240 ° C. (Pressure) 199.9 kPa (Total flow) 179 mL / min (Split ratio) 100: 1 (Split flow rate) 174 mL / Min (column) Capillary column DB1301 (length 60 m x inner diameter 0.25 mm, film thickness 1.00 μm) (column pressure) 199.9 kPa (column flow rate) 1.7 mL / min (average linear velocity) 29.0 cm / sec ( Column oven temperature program) After holding at 40 ° C. for 10 minutes, raise the temperature at 10 ° C./min and hold at 250 ° C. for 25 minutes (detector) Flame ionization detection method (FID) (detector temperature) 250 ° C.

From the gas chromatogram obtained by GC measurement, first, a peak having a peak area of 0.5 times or less the peak area of the peak derived from toluene is extracted. Here, the peaks related to the trace components contained in the present composition are extracted based on the peak area of the peak derived from toluene added to the present composition in a predetermined amount. Since the amount of acetone added to the sample solution is larger than that of toluene, the peak of acetone appears as a peak larger than the peak of toluene and is excluded during extraction. Further, since the solvent in the present composition usually has a higher content than toluene, the peak corresponding to the solvent is excluded at the time of extraction. That is, by extraction, peaks related to trace components (mainly impurity components) contained in the present composition can be extracted.

Next, the total peak area of the extracted peaks is defined as the area A.
Further, among the extracted peaks, the total peak area of the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol is defined as the area B. Since the extracted peaks do not include the peak area of the solvent-derived peak, the acetone-derived peak, and the toluene-derived peak, when calculating the area B, the solvent-derived peak and acetone The peak area of the peak derived from and the peak area of the peak derived from toluene are not included.
When calculating the area B, in order to calculate the retention time of cyclohexanol, GC measurement can be performed using cyclohexanol alone, and the retention time of cyclohexanol can be obtained in advance.
Using the obtained area A and area B, the area ratio AR is calculated by the following formula (1).
Equation (1): Area ratio AR (%) = (Area B / Area A) × 100

The range of the area ratio AR in the present composition is 0.1 to 3%, preferably 0.1 to 3.0%, preferably 0.1 to 1.5% from the viewpoint of storage stability of the present composition. Is more preferable, and 0.1 to 1.0% is particularly preferable.
When the area ratio AR is more than 3%, the storage stability of the present composition is inferior. Further, as a technical limit for removing trace components in the composition, there is a lower limit value (0.1%) of the area ratio AR. In order to make the area ratio AR less than 0.1%, it is necessary to use a very pure and expensive cyclohexyl vinyl ether, which is inferior in terms of industry.

The composition comprises a fluorinated polymer containing a predetermined unit and a solvent.
The fluorine-containing polymer contains a fluoroolefin unit and a cyclohexyl vinyl ether unit. Hereinafter, cyclohexyl vinyl ether is also referred to as "CHVE".
A fluoroolefin is an olefin in which one or more hydrogen atoms are substituted with fluorine atoms. In the fluoroolefin, one or more hydrogen atoms which are not substituted with fluorine atoms may be substituted with chlorine atoms.
As the fluoroolefin, CF ₂ = CF ₂ , CF ₂ = CFCl, CF ₂ = CFCF ₃ and CF ₂ = CH ₂ are preferable, and CF ₂ = CF ₂ (tetrafluoroethylene) and CF ₂ = CFCl (chlorotrifluoroethylene) are preferable. ) Is more preferable.
As the fluoroolefin, one type may be used alone, or two or more types may be used in combination.

The content of the fluoroolefin unit is preferably 30 to 70 mol%, more preferably 40 to 60 mol%, and particularly preferably 45 to 55 mol% with respect to all the units contained in the fluorine-containing polymer. When the content of the fluoroolefin unit is 30 mol% or more, the weather resistance of the coating film formed from the fluororesin coating film of the present invention (hereinafter, also referred to as “the present coating film”) is excellent. When the content of the fluoroolefin unit is 70 mol% or less, the solubility and dispersibility of the fluorine-containing polymer in the solvent are excellent.

The content of CHVE units is preferably 10 to 50 mol%, more preferably 10 to 45 mol%, and particularly preferably 15 to 40 mol% with respect to all the units contained in the fluorine-containing polymer. When the content of CHVE units is 10 mol% or more, the solubility and dispersibility of the fluorine-containing polymer in a solvent are excellent. When the content of CHVE units is 50 mol% or less, the weather resistance of this coating film is excellent.

The fluorine-containing polymer may contain units other than the fluoroolefin unit and the CHVE unit. Hereinafter, monomers other than fluoroolefins and CHVE will be referred to as "other monomers", and units based on the other monomers will be referred to as "other units".
The other units contained in the fluorine-containing polymer may be two or more. Further, the other unit may be a unit having a fluorine atom or a unit having no fluorine atom. Further, the other unit may be a unit having a crosslinkable group described later. Among the other units, the unit other than the unit having a crosslinkable group is the fourth unit. The fluorine-containing polymer preferably contains at least one other unit.
As the other unit, a unit having no fluorine atom is preferable. Further, the unit having no fluorine atom contained in the fluorine-containing polymer includes at least two other units of a unit having a crosslinkable group and a fourth unit (that is, a unit having no crosslinkable group). Is more preferable.
The other monomer having no fluorine atom may be a compound having no fluorine atom and having a polymerizable group, and specific examples thereof include vinyl ether, allyl ether, and vinyl having no fluorine atom. Examples include esters, allyl esters, α-olefins, acrylates and methacrylates.
As the monomer having no fluorine atom, a vinyl-based monomer having no fluorine atom is preferable, and vinyl ether and vinyl ester having no fluorine atom are more preferable from the viewpoint of reactivity with fluoroolefin. preferable.

One of the preferred embodiments of the other monomer having no fluorine atom is a monomer having a crosslinkable group (hereinafter, also referred to as “monomer I”). As will be described in detail later, when the fluoropolymer has a crosslinkable group, the fluororesin coating material contains a curing agent to improve the weather resistance, water resistance, chemical resistance, heat resistance, etc. of the present coating film. It can be further improved.
As the crosslinkable group, a functional group having an active hydrogen (hydroxy group, carboxy group, amino group, etc.), a hydrolyzable silyl group (alkoxysilyl group, etc.) and the like are preferable, and a hydroxy group is particularly preferable.

Examples of the monomer I include hydroxyalkyl vinyl ethers, hydroxyalkyl vinyl esters, hydroxyalkyl allyl ethers, hydroxyalkyl allyl esters, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, etc., which are copolymerizable with fluoroolefins and of the present coating film. From the viewpoint of weather resistance, hydroxyalkyl vinyl ether is preferable.
Specific examples of the monomer I include 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, cyclohexanedimethanol monovinyl ether, 2-hydroxyethyl allyl ether, 2-hydroxyethyl acrylate, and 2-hydroxyethyl methacrylate.
As the monomer I, one type may be used alone, or two or more types may be used in combination.

A preferred embodiment of the monomer I is a monomer represented by the following formula (2).
Equation (2) CH ₂ = CX ¹ (CH ₂ ) _n1- Q ^1- R ^1- Y
In the formula, X ¹ is a hydrogen atom or a methyl group.
n1 is 0 or 1.
Q ¹ is an oxygen atom, −C (O) O− or −O (O) C−, and an oxygen atom is preferable.
R ¹ is an alkylene group having 2 to 20 carbon atoms which may have a branched structure or a ring structure, and a cyclohexane-1,4-dimethylene group or an n-nonylene group is preferable.
Y is a crosslinkable group, preferably a hydroxy group, a carboxy group or an amino group, and more preferably a hydroxy group.

From the viewpoint of storage stability of the present composition, the content of the unit based on the monomer I is preferably 0 to 20 mol%, more preferably 0 to 18 mol%, based on all the units contained in the fluorine-containing polymer. Preferably, 0 to 15 mol% is particularly preferable.

Preferable embodiments of the monomer as the fourth unit include a monomer having no fluorine atom, cyclic hydrocarbon group, and crosslinkable group (hereinafter, also referred to as “monomer II”). ..
Examples of the monomer II include vinyl ethers, allyl ethers, vinyl esters, allyl esters, olefins, acrylates, and methacrylates having no fluorine atom, cyclic hydrocarbon group, and crosslinkable group.
Specific examples of Monomer II include nonyl vinyl ether, 2-ethylhexyl vinyl ether, hexyl vinyl ether, ethyl vinyl ether, n-butyl vinyl ether, tert-butyl vinyl ether, ethyl allyl ether, hexyl allyl ether, and carboxylic acid (acetic acid, butyric acid, pivalin). Examples thereof include vinyl esters of acids (acids, benzoic acid, propionic acid, etc.), allyl esters of carboxylic acids (acetic acid, butyric acid, pivalic acid, benzoic acid, propionic acid, etc.), ethylene, propylene, and isobutylene.
As the monomer II, one type may be used alone, or two or more types may be used in combination.

A preferred embodiment of the monomer II is a monomer represented by the following formula (3).
Equation ^{_{(3) CH 2 = CX 2}} (CH 2) n2 -Q 2 -R 2
In the formula, X ² is a hydrogen atom or a methyl group.
n2 is 0 or 1.
Q ² is an oxygen atom, a -C (O) O-or -O (O) C-.
R ² is an alkyl group having 2 to 20 carbon atoms which may have a branched structure.

From the viewpoint of storage stability of the present composition, the content of the unit based on Monomer II is preferably 0 to 50 mol%, more preferably 5 to 45 mol%, based on all the units contained in the fluorine-containing polymer. Preferably, 15-40 mol% is particularly preferred.

The contents of the fluoroolefin unit, the CHVE unit, the unit based on the monomer I, and the unit based on the monomer II are 30 to 70 mol% and 10 in this order with respect to all the units contained in the fluorine-containing polymer. It is preferably ~ 50 mol%, 0 to 20 mol%, 0 to 50 mol%.

The Mn of the fluorine-containing polymer is preferably 3000 to 40,000.
The Mw of the fluorine-containing polymer is preferably 5,000 to 100,000, more preferably 5,000 to 80,000.
When the fluorine-containing polymer is heated at 70 ° C. for 2 weeks, the Mw change rate ((Mw after heating) / (Mw before heating)) of the fluorine-containing polymer before and after heating is the fluorine-containing weight. From the viewpoint of storage stability of the coalescence, 1.50 or less is preferable, 1.40 or less is more preferable, and 1.30 or less is particularly preferable. The lower limit of the Mw rate of change is usually 1.0.
When the Mw change rate is 1.50 or less, the viscosities of the fluorine-containing polymer composition and the fluorine-based paint can be suitably maintained, and the workability when forming a coating film from the fluorine-based paint is excellent.

The present composition contains the fluorine-containing polymer and a solvent. The solvent contained in this composition is a solvent other than the solvent (toluene and acetone) used for measuring the area ratio AR by the area ratio calculation method. It is preferable that at least a part of the solvent contained in the present composition is the solvent used for producing the fluorine-containing polymer from the monomer mixture. Examples of the solvent include water and organic solvents.
As will be described later, in the method for producing a fluorine-containing polymer, the solvent used when polymerizing the monomer mixture (hereinafter, also referred to as “polymerization solvent”) is usually alcohol and an organic solvent other than alcohol. Is used. The solvent in this composition is preferably an organic solvent other than the alcohol used as the polymerization solvent. Further, the organic solvent is preferably an organic solvent having a higher boiling point than the alcohol used as the polymerization solvent.
The organic solvent in the present composition is preferably an organic solvent consisting of at least one selected from the group consisting of an aromatic hydrocarbon solvent, a ketone solvent, an ether ester solvent, an ester solvent, and a weak solvent. As the organic solvent, an organic solvent capable of dissolving the fluorine-containing polymer is preferable, and the present composition is preferably a solution containing the fluorine-containing polymer and the organic solvent in which the fluorine-containing polymer is dissolved.
The ether ester is a compound having both an ether bond and an ester bond in the molecule. A weak solvent is a solvent classified as a third-class organic solvent under the Industrial Safety and Health Act of Japan.

As the aromatic hydrocarbon solvent, xylene, ethylbenzene, aromatic petroleum naphtha, tetraline, Solbesso # 100 (registered trademark of Exxon Chemical Co., Ltd.), Solbesso # 150 (registered trademark of Exxon Chemical Co., Ltd.) and the like are preferable, and xylene and ethylbenzene are preferable. Is more preferable.
The ketone solvent is preferably acetone, methyl ethyl ketone, methyl amyl ketone, methyl isobutyl ketone, ethyl isobutyl ketone, diisobutyl ketone, cyclohexanone, or the like.
The ether ester solvent is preferably ethyl 3-ethoxypropionate, propylene glycol monomethyl ether acetate, methoxybutyl acetate and the like.
The ester solvent is preferably methyl acetate, ethyl acetate, n-propyl acetate, isobutyl acetate, t-butyl acetate and the like.
Weak solvents include gasoline, white spirit naphtha (including solvent naphtha), petroleum ether, petroleum naphtha, petroleum benzine, terepine oil, mineral spirit (including mineral thinner, petroleum spirit, white spirit, mineral tarpen), etc. Mineral spirit is preferable because it is at least one selected from the group and the ignition point is at room temperature or higher.

The solvent may consist of only one type of solvent, or may be a mixed solvent of two or more types.
The content of the solvent in the present composition is preferably 30 to 70% by mass, more preferably 45 to 70% by mass, based on the total mass of the present composition.

In addition, the present composition may contain a residue of a monomer used to obtain a fluorine-containing polymer and a component of a raw material used for producing the monomer, and these components are described above. It may correspond to a trace amount component (impurity component).
Specific examples of the residue of the monomer used to obtain the fluorine-containing polymer include the residue of cyclohexyl vinyl ether and the residue of the above-mentioned monomer I (4-hydroxyvinyl ether, etc.). ..
Moreover, as a specific example of the raw material used for producing a monomer, cyclohexanol used for producing a cyclohexyl vinyl ether can be mentioned.

The present invention is also two production methods for producing a fluorine-containing polymer having excellent storage stability. The first production method of the production method of the present invention is a method in which CHVE is purified before polymerization and the purified CHVE is used to produce a fluorine-containing polymer. In the second production method of the production method of the present invention, after polymerizing a monomer to produce a fluorine-containing polymer, when alcohol that is a part of a polymerization solvent is distilled off from the reaction mixture, the alcohol is used. This is a method for producing a fluorine-containing polymer by accumulating under stricter conditions than normally required for removal and simultaneously removing impurity components.
In any of the production methods of the present invention, the fluorine-containing polymer obtained by the method has high storage stability due to a small content of impurity components caused by monomers and the like, and has a viscosity even in a solvent solution thereof. There is little change. Further, by carrying out the two manufacturing methods at the same time, the content of the impurity component can be further reduced as compared with the case where the individual manufacturing methods are carried out.
All of the production methods of the present invention are suitable methods for producing the fluorine-containing polymer composition of the present invention. However, the production method of the present invention is not limited to the production of the present composition, and the fluorine-containing polymer obtained by the production method of the present invention is a fluorine-containing polymer solution or dispersion other than the present composition. It can also be used in the production of.
Hereinafter, the production method of the present invention will be described by taking the production of the present composition as an example.

The first production method of the present invention is a method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and CHVE, from cyclohexanol contained together with CHVE by purifying CHVE. Is also a production method characterized in that CHVE having the following area ratio of a low boiling point compound of 0.15% or less is used, and the purified CHVE is used for the polymerization.
Area ratio: In the measurement of CHVE by gas chromatography, the sum of the peak areas of the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol with respect to the sum of the peak areas of all the peaks in the obtained gas chromatogram. Percentage of.
The present inventors have found that most of the components appearing on the shorter side than the retention time of cyclohexanol in the GC measurement are low boiling point compounds contained in CHVE used as a raw material. Further, it is considered that this low boiling point compound is at least a part of the impurity component that lowers the storage stability of the fluorine-containing polymer solution. Therefore, if the amount of the low boiling point compound contained together with CHVE is reduced by distillation of CHVE, a fluorine-containing polymer having excellent storage stability can be produced. In addition, the area ratio AR in the fluorine-containing polymer composition of the present invention can be reduced. That is, the fluorine-containing polymer composition of the present invention can be produced by this first production method.
The area ratio is preferably 0.1% or less, more preferably 0.05% or less, and particularly preferably 0.01% or less. The lower limit is not particularly limited and is 0%.
As a method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and CHVE, a known method can be used except that purified CHVE is used. As the polymerization medium, a solvent or a dispersion medium can be used, and it is preferable to use an organic solvent capable of dissolving the produced fluorine-containing polymer. Further, the same production method as the second production method described later is preferable except for the conditions for distilling off alcohol under reduced pressure, and it is more preferable to use the second production method described later including the conditions for distilling off alcohol under reduced pressure.

The second production method of the present invention is a method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and CHVE in the presence of a radical polymerization initiator, an alkali metal carbonate and a polymerization solvent. The polymerization solvent is a mixed solvent of an alcohol having 1 to 6 carbon atoms and an organic solvent having a boiling point higher than that of the alcohol by 20 ° C. or higher (hereinafter, also referred to as “high boiling point organic solvent”), and is a reaction mixture after polymerization. The alcohol was distilled off under reduced pressure to remove the precipitated alkali metal carbonate, and the alcohol was distilled off under reduced pressure to exceed the temperature and degree of reduced pressure normally used for distillation under reduced pressure of the alcohol, and the organic solvent was used. It is a production method characterized by obtaining a fluorine-containing polymer dissolved in the organic solvent by carrying out under the condition that the distillation is not carried out under reduced pressure.
In the second production method, removal conditions stricter than the usual alcohol removal conditions are set so that the low boiling point compound is also removed when the alcohol having 1 to 6 carbon atoms is removed. For example, when the alcohol is distilled off under reduced pressure, the low boiling point compounds are also removed by distillation under reduced pressure under lower pressure conditions or higher temperature conditions. On the other hand, the boiling point difference between the alcohol used and the high boiling point organic solvent is preferably larger so that even the high boiling point organic solvent is not removed when the alcohol is removed, and the boiling point of the high boiling point organic solvent is the same as that of the alcohol used in combination. It is preferably 30 ° C. or higher, more preferably 50 ° C. or higher than the boiling point.
Ethanol is preferable as the alcohol having 1 to 6 carbon atoms, and more specifically, when ethanol is used, it is 45 Torr or less (preferably 30 Torr or less) at a temperature of 65 ° C. or higher (the upper limit is preferably 85 ° C.). The lower limit is preferably 5 Torr), and the distillation is preferably carried out under reduced pressure.
Further, by this second production method, the area ratio AR in the polymer composition of the present invention can be reduced. That is, the fluorine-containing polymer composition of the present invention can be produced by this second production method.

From the viewpoint of productivity, the second production method of the present invention preferably has the following steps 1 to 3.
Step 1 (Polymerization Step): Polymerization of a monomer mixture containing fluoroolefin and CHVE as a mixed solvent of a radical polymerization initiator, an alkali metal carbonate, and an alcohol having 1 to 6 carbon atoms and a high boiling point organic solvent. A step of copolymerizing in a state where at least a part of an alkali metal carbonate is dissolved in the above-mentioned polymerization solvent in the presence of a solvent to obtain a solution of a fluorine-containing polymer.
Step 2 (precipitation step): A step of removing the alcohol from the solution of the fluoropolymer to reduce the content of the alcohol and precipitating an alkali metal carbonate.
Step 3 (removal step): A step of filtering the solution of the fluorine-containing polymer obtained in the above step 2 to remove the precipitated alkali metal carbonate to obtain a fluorine-containing polymer dissolved in a high boiling point organic solvent.

In addition to the fluoroolefin and CHVE, the monomer mixture in step 1 may contain other monomers (monomer I, monomer II, etc.), if necessary.
Specific examples of the alkali metal carbonate used in step 1 include potassium carbonate.
The mass ratio of the alkali metal carbonate to all the monomers in the monomer mixture (all monomers in the alkali metal carbonate / monomer mixture) in step 1 was 0.005 / 1 to 0. 013/1 is preferable, and 0.008 / 1 to 0.012 / 1 is more preferable. When the mass ratio of potassium carbonate to all the monomers in the monomer mixture is 0.005 / 1 or more, the copolymerization reaction proceeds smoothly and all the monomers in the potassium carbonate and monomer mixture. When the mass ratio with and is set to 0.013 / 1 or less, it is possible to suppress the coloring of the obtained fluoropolymer solution while ensuring the polymerization stability.
The polymerization solvent in step 1 may contain an alcohol having 1 to 6 carbon atoms and a high boiling point organic solvent, and in addition to these solvents, conventionally known solvents used for polymerization can be used.
When the present composition is produced, no special treatment such as solvent substitution is required. Therefore, the solvent contained in the present composition is the same as the high boiling point organic solvent in the polymerization solvent, and the present composition can be obtained in step 3. It is preferable to use the fluorine-containing polymer solution as it is as the present composition.

Specific examples of the alcohol having 1 to 6 carbon atoms include methanol, ethanol, n-propanol, i-propanol, tert-butanol, pentanol, and hexanol, and ethanol is preferable from the viewpoint of solubility of potassium carbonate.
Examples of the high boiling point organic solvent in the polymerization solvent include an aromatic hydrocarbon solvent, an alcohol solvent other than alcohol having 1 to 6 carbon atoms, a ketone solvent, an ether ester solvent, an ester solvent, a weak solvent, and the like in the polymerization medium. Examples thereof include organic solvents having a boiling point higher than that of alcohol by 20 ° C. or higher. Specific examples of the aromatic hydrocarbon solvent, the ketone solvent, the ether ester solvent, the ester solvent, and the weak solvent are organic solvents that satisfy the high boiling point condition among the solvents preferably contained in the present composition.
Specific examples of alcohol solvents other than alcohols having 1 to 6 carbon atoms include octyl alcohol and dodecyl alcohol.
The high boiling point organic solvent is more preferably an aromatic hydrocarbon solvent, an ether ester solvent, or an alcohol solvent other than an alcohol having 1 to 6 carbon atoms, and an aromatic hydrocarbon solvent is particularly preferable.
When the alcohol having 1 to 6 carbon atoms is ethanol (bp: 78 ° C.), the high boiling point organic solvent is preferably an organic solvent having a boiling point of 110 ° C. or higher, specifically toluene (bp: 110 ° C.) and ethylbenzene. Examples thereof include aromatic hydrocarbon solvents such as (bp: 136 ° C.) and xylene (bp: 138 to 144 ° C.).
The content of the alcohol having 1 to 6 carbon atoms with respect to the total mass of the polymerization solvent is preferably 10 to 95% by mass, more preferably 20 to 90% by mass.

The monomer mixture is preferably copolymerized by solution polymerization in the presence of a radical polymerization initiator, an alkali metal carbonate, and the polymerization solvent in a state where at least a part of potassium carbonate is dissolved.
The "state in which at least a part of the alkali metal carbonate is dissolved" means that a part of the alkali metal carbonate is dissolved in the solvent, but at least a part of the alkali metal carbonate is not dissolved and dispersed (suspended or precipitated). It is a state in which it may be (including).

Specific examples of the radical polymerization initiator include azo-based initiators (2,2'-azobisisobutyronitrile, 2,2'-azobiscyclohexanecarbonatenitrile, 2,2'-azobis (2,4-dimethyl). Valeronitrile), 2,2'-azobis (2-methylbutyronitrile), etc.), ketone peroxide (cyclohexanone peroxide, etc.), hydroperoxide (tert-butylhydroperoxide, etc.), diacyl peroxide (benzoylper) Oxide, etc.), Dialkyl peroxide (di-tert-butyl peroxide, etc.), Peroxyketal (2,2-di- (tert-butylperoxy) butane, etc.), Alkyl peroxide (tert-butylperoxypivalate, etc.) (PBPV), etc.), peroxide-based initiators of percarbonates (diisopropylperoxydicarbonate, etc.) can be mentioned.

When it is necessary to adjust Mn and Mw of the fluorine-containing polymer, a conventionally known chain transfer agent may be added as necessary.

The polymerization reaction is preferably carried out under the conditions that the polymerization temperature is 65 ° C. ± 10 ° C. and the polymerization time is 6 hours to 36 hours. The polymerization temperature may be appropriately set according to the decomposition start temperature and the half-life of the initiator to be used. The polymerization reaction may be stopped by a polymerization inhibitor such as hydroquinone monomethyl ether after cooling.

In step 2, the alcohol solvent having 1 to 6 carbon atoms is removed from the solution of the fluorine-containing polymer obtained in step 1, preferably reduced to 0 to 0.03% by mass with respect to the polymerization solvent, and the alkali metal. This is a step of precipitating carbonate in a solution.
Examples of the method for removing alcohol having 1 to 6 carbon atoms include a method of concentrating under reduced pressure heating with a vacuum distillation apparatus.

It is preferable to perform prefiltration before removing the alcohol having 1 to 6 carbon atoms. Preliminary filtration is performed for the purpose of roughly filtering alkali metal carbonates or alterations thereof, which are dispersed (including floating or precipitation) as solids in the solution of the fluorine-containing polymer. If pre-filtration is not performed, these may be removed in the following removal step.

In step 3, the solution of the fluorine-containing polymer obtained in the precipitation step from which the alcohol solvent having 1 to 6 carbon atoms had been removed was filtered to remove the precipitated alkali metal carbonate and dissolved in an organic solvent. This is a step of obtaining a fluorine-containing polymer.

Examples of the filtration method include filtration using diatomaceous earth. Examples of the diatomaceous earth include diatomaceous earth having an intermediate particle size of 25 to 40 μm, and the amount used thereof is preferably ^{0.05 to 0.10 g / cm 2 with respect to the filtration area.}
Specifically, the filtration was performed using the diatomaceous earth, and the filter paper No. 1 for viscous liquid was used. It is preferable to transfer the liquid to a pressure filter equipped with 63, filter under a pressure condition of 0.01 to 0.5 MPa, and circulate filter until the appearance of the filtrate is visually free of haze.

This composition can be suitably used for fluororesin paints (clear paints, etc.).
The fluororesin paint of the present invention can be prepared by further adding a paint compounding component such as a curing agent and a resin other than the fluoropolymer to the composition.
The fluororesin paint may be a one-component type paint or a two-component type paint. In the case of the two-component type, the curing agent is preferably mixed immediately before use.

When the fluorine-containing polymer contains a unit based on the monomer I, the curing agent is preferably a curing agent capable of crosslinking with the crosslinkable group of the monomer I.
When the crosslinkable group of the monomer I is a hydroxyl group, the curing agent is preferably a curing agent for coating materials such as a room temperature curing type isocyanate curing agent, a thermosetting type blocked isocyanate curing agent, and a melamine curing agent.
The content of the curing agent in the fluororesin coating material is preferably 1 to 100 parts by mass, more preferably 1 to 50 parts by mass with respect to 100 parts by mass of the fluoropolymer.

As the resin other than the fluororesin-containing polymer, a known resin blended in the fluororesin coating material can be appropriately used.
In order to improve the drying property of the coating film, CAB (cellulose acetate butyrate), NC (nitrocellulose) and the like may be blended. Further, in order to improve the gloss, hardness and workability of the paint film, a paint resin such as a polymer composed of acrylic acid or an ester thereof and polyester may be blended.

In addition, known ingredients to be blended in the paint, such as a silane coupling agent, an ultraviolet absorber, a curing accelerator, a light stabilizer, a colorant, and a matting agent, can be blended as an additive, if necessary.

The coated article of the present invention has a coating film formed on the surface of the article by the fluororesin coating material of the present invention.
Specific examples of articles to be painted include transportation equipment (automobiles, trains, aircraft, etc.), civil engineering members (bridge members, steel towers, etc.), industrial equipment (waterproof material sheets, tanks, pipes, etc.), and building members (building exteriors). , Doors, window gate members, monuments, poles, etc.), road members (road central separation zone, guard rails, soundproof walls, etc.), communication equipment, electrical and electronic parts, surface sheets and back sheets for solar cell modules. ..
The film thickness of the coating film is preferably 10 to 200 μm, more preferably 10 to 100 μm.

The fluororesin paint may be applied directly to the surface of the article, or may be applied after applying a known surface treatment (base treatment or the like) to the surface of the article.
Specific examples of the method for applying the fluororesin paint include spray coating, air spray coating, brush coating, dipping method, roll coater, and flow coater.
The drying temperature after coating is preferably about 15 ° C. to 300 ° C.

Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to these examples.
The evaluation methods and materials used in each example are shown below.

<Calculation of area ratio AR>
It was calculated according to the area ratio calculation method described above.
Prepare the fluorine-containing polymer composition produced in Examples and Comparative Examples described later, and add 200 parts by mass of acetone (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) to 100 parts by mass of the fluorine-containing polymer composition. To prepare a diluted solution obtained by diluting the fluorine-containing polymer composition.
Next, 1% by mass of toluene (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent) was added to the diluted solution to prepare a sample solution. Using the obtained sample solution, GC measurement was performed under the above-mentioned conditions using a 6850 Series II (detector: FID) manufactured by Agilent Technologies. From the obtained chromatogram, the area ratio AR was determined by the method described above. The retention time of cyclohexanol was confirmed by measuring cyclohexanol (manufactured by Wako Pure Chemical Industries, Ltd., special grade reagent).

<Evaluation of storage stability>
The fluorine-containing polymer compositions produced in Examples and Comparative Examples described later were placed in a closed container and heated in an oven set at 70 ° C. for 2 weeks. The rate of change in Mw of the fluorine-containing polymer before and after heating was evaluated.
Mw rate of change = (Mw after heating) / (Mw before heating)
For the measurement of Mw, an apparatus: EcoSEC HLC-8320GPC manufactured by Toso Co., Ltd. was used, and as a sample solution for evaluating Mw, the fluorine-containing polymer composition was diluted with tetrahydrofuran and the concentration of the fluorine-containing polymer was 1 mass. The sample solution prepared to% was used.

<CHVE>
In the following examples and comparative examples, CHVE1 to 3 shown in Table 1 below were used. In the "Area ratio (%) of compound having a boiling point lower than that of cyclohexanol" in Table 1, the peaks of all the peaks in the gas chromatogram obtained by performing the above-mentioned GC measurement using each CHVE. It represents the ratio (area ratio) of the total peak area of the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol with respect to the total area. The lower the area ratio, the smaller the proportion of components having a lower boiling point than cyclohexanol.
CHVE3 is a commercially available product, CHVE1 is CHVE (distillation yield 70%) obtained by distilling CHVE3, and CHVE2 is CHVE (distillation yield 90%) obtained by distilling CHVE3. ).

(Example 1)
Xylene (587 g), ethanol (168 g), ethyl vinyl ether (EVE) (206 g), 4-hydroxy vinyl ether (HBVE) (129 g), cyclohexyl vinyl ether 1 (CHVE1) in a stainless steel pressure-resistant reactor with a stirrer (internal volume 2500 mL). ) (208 g), potassium carbonate (11 g), and tert-butyl peroxypivalate (PBPV) (3.5 g) were charged, and dissolved oxygen in the liquid was removed by pressurization / purging with nitrogen and degassing.
Then, chlorotrifluoroethylene (CTFE) (660 g) was introduced, the temperature was gradually raised, and the reaction was continued while maintaining the temperature at 65 ° C. After 12 hours, the reactor was cooled with water to stop the reaction. After cooling the reaction solution to room temperature, the unreacted monomer was purged and the reactor was opened.
The obtained reaction solution was used as a viscous filter paper No. The liquid was transferred to a pressure filter equipped with 63, potassium carbonate was filtered off at a pressure of 0.05 MPa, and then 0.1 g of hydroquinone monomethyl ether (HQMME) was added. Then, ethanol in the reaction solution was distilled off by a vacuum distillation apparatus under reduced pressure heating at 65 ° C. and 45 Torr. Next, 0.06 g / cm ² of diatomaceous earth (intermediate particle size 30.1 μm) with respect to the filtered area was added to the reaction solution, mixed and stirred, and then the viscous filter paper No. The liquid was transferred to a pressure filter equipped with 63, filtered twice at a pressure of 0.02 MPa, and the diatomaceous earth was filtered off to obtain a fluorine-containing polymer composition P1.
Then, the concentration was adjusted so that the mass concentration of the fluorine-containing polymer in the fluorine-containing polymer composition P1 was 60% by mass, and the fluorine-containing polymer composition 1 was obtained.
Next, as a result of analyzing the fluorine-containing polymer composition 1 by the above-mentioned GC measurement, it was confirmed that the area ratio AR was 0.8%.

(Example 2)
A fluorine-containing polymer composition 2 was obtained according to the same procedure as in Example 1 except that CHVE2 was used instead of CHVE1.
Next, as a result of analyzing the fluorine-containing polymer composition 2 by the above-mentioned GC measurement, it was confirmed that the area ratio AR was 3.0%.

(Example 3)
Xylene (587 g), ethanol (168 g), EVE (206 g), HBVE (129 g), CHVE2 (208 g), potassium carbonate (11 g) and PBPV (3. 5 g) was charged, and dissolved oxygen in the liquid was removed by pressurizing / purging with nitrogen and degassing.
Then, CTFE (660 g) was introduced to gradually raise the temperature, and the reaction was continued while maintaining the temperature at 65 ° C. After 12 hours, the reactor was cooled with water to stop the reaction. After cooling the reaction solution to room temperature, the unreacted monomer was purged and the reactor was opened.
The obtained reaction solution was used as a viscous filter paper No. The liquid was transferred to a pressure filter equipped with 63, potassium carbonate was filtered off at a pressure of 0.05 MPa, and then 0.1 g of HQMME was added. Then, ethanol in the reaction solution was distilled off by a vacuum distillation apparatus under reduced pressure heating at 65 ° C. and 15 Torr. Next, 0.06 g / cm ² of diatomaceous earth (intermediate particle size 30.1 μm) with respect to the filtered area was added to the reaction solution, mixed and stirred, and then the viscous filter paper No. The liquid was transferred to a pressure filter equipped with 63, filtered twice at a pressure of 0.02 MPa, and the diatomaceous earth was filtered off to obtain a fluorine-containing polymer composition P3.
Then, the concentration was adjusted so that the mass concentration of the fluorine-containing polymer in the fluorine-containing polymer composition P3 was 60% by mass, and the fluorine-containing polymer composition 3 was obtained.
Next, as a result of analyzing the fluorine-containing polymer composition 3 by the above-mentioned GC measurement, it was confirmed that the area ratio AR was 1.3%.

(Comparative Example 1)
A fluorine-containing polymer composition 4 was obtained according to the same procedure as in Example 1 except that CHVE3 was used instead of CHVE1.
Next, as a result of analyzing the fluorine-containing polymer composition 4 by the above-mentioned gas chromatography measurement, it was confirmed that the area ratio AR was 5.0%.

The above-mentioned storage stability evaluation was carried out using the fluorine-containing polymer compositions obtained in each of the above Examples and Comparative Examples. The results are summarized in Table 2 below.

As shown in Table 2, it was confirmed that the present composition showing a predetermined area ratio AR is excellent in storage stability.
The entire contents of the specification, claims and abstract of Japanese Patent Application No. 2016-139553 filed on July 14, 2016 are cited here and incorporated as disclosure of the specification of the present invention. Is.

Claims (13)

A composition comprising a fluoropolymer containing a fluoroolefin unit and a cyclohexyl vinyl ether unit and a solvent (excluding toluene and acetone).
A fluorine-containing polymer composition characterized in that the area ratio AR obtained by the following area ratio calculation method is 0.1 to 3%.
Area ratio calculation method: Add 200 parts by mass of acetone to 100 parts by mass of the fluorine-containing polymer composition to prepare a diluted solution obtained by diluting the fluorine-containing polymer composition, and further add to the total mass of the diluted solution. On the other hand, 1% by mass of toluene was added to the diluted solution to prepare a sample solution, and gas chromatography measurement was carried out using the obtained sample solution to obtain 0.5 times the peak area of the peak derived from toluene. A peak having the following peak areas is extracted, and the sum of the peak areas of the extracted peaks is defined as area A, which is derived from a component of the extracted peaks that appears on the side shorter than the retention time of cyclohexanol. Let the sum of the peak areas of the peaks be the area B, and let the value obtained by the following equation (1) be the area ratio AR.
Equation (1): Area ratio AR (%) = (Area B / Area A) × 100 The content of the fluoroolefin unit is 30 to 70 mol% with respect to all the units contained in the fluorine-containing polymer.
The fluorine-containing polymer composition according to claim 1, wherein the content of the cyclohexyl vinyl ether unit is 10 to 50 mol% with respect to all the units contained in the fluorine-containing polymer. The fluorine-containing polymer composition according to claim 1 or 2, wherein the area ratio AR is 0.1 to 1.5%. The fluorine-containing polymer composition according to any one of claims 1 to 3, wherein the fluoroolefin unit is a tetrafluoroethylene unit or a chlorotrifluoroethylene unit. The fluorine-containing polymer composition according to any one of claims 1 to 4, wherein the fluorine-containing polymer further contains a unit having a crosslinkable group. The fluorine-containing polymer composition according to claim 5, wherein the unit having a crosslinkable group is a unit having a hydroxyl group. The invention according to any one of claims 1 to 6, wherein the fluorine-containing polymer further contains a unit based on a fourth monomer other than a fluoroolefin, a cyclohexyl vinyl ether and a monomer having a crosslinkable group. Fluorine-containing polymer composition. The fluorine-containing polymer composition according to claim 7, wherein the unit based on the fourth monomer is a unit based on a monomer having no fluorine atom. A method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and a cyclohexyl vinyl ether, wherein the cyclohexyl vinyl ether is purified and contained in the cyclohexyl vinyl ether, cyclohexanol. A method for producing a fluorine-containing polymer, which comprises using a cyclohexyl vinyl ether having the following area ratio of a compound having a boiling point lower than that of 0.15% or less, and using the purified cyclohexyl vinyl ether for the polymerization. ..
Area ratio: In the measurement of cyclohexyl vinyl ether by gas chromatography, the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol with respect to the sum of the peak areas of all the peaks in the obtained gas chromatogram. Percentage of total area. The method for producing a fluorine-containing polymer according to claim 9, wherein the monomer mixture is polymerized in the presence of a solvent or a dispersion medium. A method for producing a fluorine-containing polymer by polymerizing a monomer mixture containing a fluoroolefin and a cyclohexyl vinyl ether in the presence of a radical polymerization initiator, an alkali metal carbonate and a polymerization solvent.
The cyclohexyl vinyl ether contains a compound having a boiling point lower than that of cyclohexanol, and the following area ratio of the compound is 0.15% or less, and the polymerization solvent is ethanol and 20 ° C. than that of ethanol. The alkali metal carbonate precipitated by distilling off the ethanol from the reaction mixture after polymerization under reduced pressure, which is a mixed solvent with the organic solvent having a high boiling point, the organic solvent has a boiling point of 110 ° C. or higher. A method for producing a fluorine-containing polymer, which comprises removing the ethanol under reduced pressure and distilling off the ethanol under reduced pressure at a temperature of 65 ° C. or higher and a reduced pressure of 45 Torr or lower to obtain a fluorine-containing polymer dissolved in the organic solvent.
Area ratio: In the measurement of cyclohexyl vinyl ether by gas chromatography, the peaks derived from the components appearing on the side shorter than the retention time of cyclohexanol with respect to the sum of the peak areas of all the peaks in the obtained gas chromatogram. Percentage of total area. A fluororesin coating material containing the fluorine-containing polymer composition according to any one of claims 1 to 8. A painted article comprising the article and a coating film formed on the article from the fluororesin paint according to claim 12.